<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<script type="text/javascript">
		var a=10;
		var b=2;
		alert(a*b);
		alert(a-b);
		alert(a+b);
		alert(a/b);
		var c=12;
		var d="12";
		alert(c==d);
		alert(c===d);
		var arr=[];
		arr[0]=undefined;
		arr[2]=1;
		var arr1=[true,1];
		for (var i = 0; i < arr.length; i++) {
			alert(arr[i])
		}
		var a=new Array(3);
		document.write("这个数字是"+i+"<br/>")
		</script>
	</head>
	<body>
	</body>
</html>
